[PATCH] D91716: AMDGPU/GlobalISel: Calculate isKnownNeverNaN for fminnum and fmaxnum
Petar Avramovic via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Wed Nov 18 08:49:04 PST 2020
Petar.Avramovic added inline comments.
================
Comment at: llvm/test/CodeGen/AMDGPU/GlobalISel/legalize-fminnum.mir:773
%3:_(s32) = COPY $vgpr2
%4:_(s32) = G_FMINNUM %2, %3
$vgpr0 = COPY %4
----------------
```
return isKnownNeverNaN(Op.getOperand(0), SNaN, Depth + 1) ||
isKnownNeverNaN(Op.getOperand(1), SNaN, Depth + 1);
}
```
This is legalized first. `%2` is isKnownNeverSNaN with IEEE = true, but since inputs for `%2:_(s32) = G_FMAXNUM %0, %1` are not yet canonicalized isKnownNeverSNaN will fail and canonicalize is inserted. However since we know what will happen with `'%2:_(s32) = G_FMAXNUM %0, %1` we declare it isKnownNeverSNaN to not depend on order of legalization.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D91716/new/
https://reviews.llvm.org/D91716
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